FR2628062A1 - BLADE FOR HIGH-PERFORMANCE CARENEE PROPELLER, MULTI-PURPOSE CARENEE PROPELLER PROVIDED WITH SUCH BLADES AND TAIL ROTOR ARRANGEMENT IN HELICE CARENEE FOR ROTARY-BOAT AIRCRAFT - Google Patents

Abstract

Blade for faired propeller. According to the invention, this blade is remarkable: - in that, in plan, its aerodynamically active part has a rectangular shape; and in that : . the relative maximum camber of the successive profiles constituting the aerodynamically active part of the blade increases from a value close to 0 to a value close to 0.04; . the twist v of the aerodynamically active part of the blade decreases from a first value close to 12degre (s) up to a second value close to 4degre (s), then increases to a third value close to 4.5degre ( s); and. the relative maximum thickness of said successive profiles decreases from a value close to 13.5% to a value close to 9.5%. Realization of high performance ducted propellers and in particular tail rotor arrangement for rotary wing aircraft.

Description

(") FRENCH REPUBLIC Publication No. 2,628,062 (to be used only

  for INSTITUTE NATIONAL Reproduction Orders)

OF PROPERTY [INDUSTRIAL TEA

  OF INDUSTRIAL PROPERTY N of national registration 88 02873 PARIS

(3 Int CI ': B 64C 11/18.

  APPLICATION FOR PATENT OF INVENTION A1

  (Filing date March 7, 1988. t Applicant (s): AEROSPATIALE public limited company,

  NATIONAL INDUSTRIAL COMPANY. - FR.

() Priority

  (& Inventor (s): Alain Eric Vuillet.

  - Date of the public availability of the

  BOPI application "Patents" No. 36 of 8 September 1989.

  6 References to other national documents appearing

: Holder (s)

(Attorney (s): Propi Conseils.

  Blade for high-performance faired propeller, multi-blade faired propeller provided with such blades and arrangement of

  fan propeller tail rotor for rotary wing aircraft.

@ Blade for faired propeller.

  According to the invention this blade is remarkable - in that, in plan, its aerodynamically active portion has a rectangular shape; and in that:

  the maximum relative camber of the successive profiles constituting

  killing the aerodynamically active part of the blade increases by a value close to 0 to a value close to 0.04; yf. the twist v of the aerodynamically active part of the blade decreases from a first value close to 12 to a second value close to 4, then increases to a third value close to 4.5; and the relative maximum thickness of said successive profiles d 1 / N increases from a value of 13.5% / o to a value close to

9.5%.

  O Realization of high performance streamlined propellers and in particular tail rotor arrangement for aircraft with

rotating wing.

{O i.

1i 2628062.

  The present invention relates to blades for high-performance keeled propellers, as well as keeled propellers provided with a plurality of such blades. Its object is to increase the thrust or traction delivered by such a faired propeller and, correspondingly, to reduce the power required to drive the rotating propeller. Although not exclusively, the present invention is particularly suitable for use with auxiliary tail rotors of

rotary wing aircraft.

  We know that, compared to a free helix of the same

  diameter, a faired helix in a vein

  to obtain a significant increase in thrust or traction

  equal, with a power gain of the order of 30%.

  Indeed, the vein improves the efficiency of the propeller installed inside, compared to a free propeller, for two reasons: - the circulation of air through the vein creates a depression on the hull and therefore a thrust the fairing as a whole, which is substantially equal to the thrust of the propeller itself; - The flow in the vicinity of the hull being in depression downstream of the propeller, the flow does not contract, unlike what happens downstream of a free propeller, which has the effect of increasing the yield of the helix and all the more so as it increases the diffusion of the fluid vein without stalling in the hull. This is why in many applications in which, in a limited space, it is a question of creating a force of aerodynamic origin by a propeller, the

  The solution of a faired propeller proved to be more

  than that brought by a free propeller.

2 2628062

  1 These applications include vertical take-off and landing aircraft, in which one or more vertical-axis careened propellers are integrated in the fixed wing or the fuselage, the air-lift vehicles whose generator (s) pressure air blowing towards the ground are propellers housed inside fairings, themselves incorporated in the body of the vehicle, and finally the variable pitch fans, for example those incorporated in a gas pipe for create a significant circulation of this

last in the driving.

  A particularly interesting application has been

  made to realize the tail rotor of the helicopters.

  It is known that on these lift-wing rotary aircraft, and in particular on the mechanical-powered single-rotor helicopters, to continuously balance the reaction torque on the fuselage resulting from the rotational drive of the rotary wing, as well as to control the aircraft on its yaw axis, there is provided an auxiliary rotor disposed near the end of the tail of the aircraft and exerting a transverse thrust that is adaptable to all flight conditions. This auxiliary tail rotor thus exerts on the aircraft an equilibrium torque in the opposite direction to the reaction torque of the main rotor when it is rotated by the engine or motors, that is to say in the same direction as the training torque of the wing

rotating lift.

  Controlled variations of this balance torque by the pitch control of the anti-torque auxiliary rotor blades also enable the pilot to control the helicopter.

in cape around its yaw axis.

3 2628062

  1 However, and particularly on helicopters of low or medium tonnage, the conventional anti-torque rotor constituted by a free propeller is particularly vulnerable to external aggression: it can affect the personnel on the ground or touch the ground itself or not. any obstacle, any collisions that directly compromise the balance of the helicopter and its safety flight. In particular, in order to avoid these serious drawbacks, the plaintiff has developed on the helicopters of light and medium tonnages, a multipale tail rotor arrangement, careened inside the vertical drift of

these devices.

  Such an installation is made possible and advantageous by the fact that the diameter of such a streamlined rotor can be relatively small compared to that of a free rotor

of equivalent effectiveness.

  Such anti-torque keyless rotor arrangements are

  example described in US-A-3,506,219, US-A-

3,594,097 and US-A-4,281,966.

  Of course, it is sought to obtain from this auxiliary rotor, under the best performance conditions as regards the driving power, a maximum thrust, sufficiently high to satisfy the most demanding flight conditions and is provided by the control of the not blades, to take only part of this maximum thrust adapted to other cases of theft. It is known that the lift efficiency of rotary wings is generally characterized for stationary operating conditions by a parameter known as the "Merit Figure" which is the ratio

4 2628062

  between the minimum power to obtain a given traction or thrust and the actual power actually measured. For a careened helix, the expression of this parameter is given by the following known formula:

FM = 1 T

2VU P -

  where FM is the figure of merit, T is the desired thrust or pull, P is the power required to provide the helix, p is the density of the air, R is the radius of the helix, and

  o the diffusion coefficient of the aerodynamic flow

  than on the surface, this coefficient being equal to the ratio S-

  S with S- representing the surface of the flux at infinity downstream and S being the surface of the disk formed by the rotating helix. To increase the figure of merit with fixed power and size, it is therefore necessary to increase the

  pushing or pulling the propeller.

  The present invention particularly relates to a blade for

  faired propeller, whose geometry of the aerodynamic part

  The active gear is optimized for the propeller to deliver as much thrust or traction as possible while consuming as little power as possible for training. To this end, according to the invention, the blade for faired propeller comprising a tunnel and a rotor with multiple blades coaxial with said tunnel, said rotor comprising a rotary hub whose radius is of the order of 40% of that of said tunnel and sure

262,806?

  1 which said blades are mounted via blade roots, is remarkable: - in that, in plan, the aerodynamically active portion of said blade has, beyond the blade root, a rectangular shape so that the successive profiles constituting said aerodynamically active portion all have the same rope 1 and that the end section of said aerodynamically active portion is straight; and in that, along the span of the blade counted from the axis of the tunnel, between a first section whose relative span (that is to say, relative to the total span of the blade) is close to 45% and the end section of said blade: the maximum relative camber of the successive profiles constituting said aerodynamically active portion of the blade is positive and increases from a value close to 0 to a value close to 0, 04; the twisting of said aerodynamically active part of the blade decreases from a first value close to 12 to said first section to a second value close to 4 to a second section whose relative span is close to 0.86, then increases from this second section to a third value close to 4.50 at said blade end section; and 25. the relative maximum thickness of said successive profiles decreases from a value close to 13.5% to a

value close to 9.5%.

  The Applicant has found that such a combination of camber, twisting and thickness profiles, associated with a rectangular shape of the blades (the leading edge and the trailing edge being rectilinear and parallel), led to a blade with excellent

  aerodynamic properties (shown below) and excellent

  your mechanical strength properties, in particular by increasing the blade section in the vicinity of

the root on the hub.

6 262806?

  According to other advantageous features of the present invention:

  a) said relative maximum camber increases almost linearly

  this value close to 0 to a value equal to 0.036 for a relative span equal to 0.845, passing through the values 0.01 and 0.02 respectively for the relative spans 0.53 and 0.66, then increases by this value equal to 0.036 for the relative span equal to 0.845 up to a value equal to 0.038 for the relative span equal to 0.93, and finally is constant and equal to 0.038 between the relative percentages 0, 93 and 1; b) the foot of said blade has evolutionary profiles whose relative maximum camber is negative and increases by a value substantially equal to -0.013 for a relative span equal to 0.40 to said value close to

  0 for a relative span equal to 0.45.

  c) between the relative sizes 0.45 and 1, the twisting evolution is at least substantially parabolic, with a

  minimum to the relative extent of 0.86.

  d) the twisting axis of said aerodynamically active portion is parallel to the leading edge line and the trailing edge line thereof and is remote from

  said leading edge line by an approximate distance

  39% of the length of the chord of the profiles.

  e) the kinking of the foot of said blade increases from said value close to 80 to a relative span close to 0.38 to said value close to 120 for the span

relative equals 0.45.

2628062.

  1 f) the relative maximum thickness of the profiles decreases linearly from a value close to 13.9% for a relative span equal to 0.40 to a value close to 9.5% for a relative span equal to 0.93, and is constant and equal to said value close to 9.5% between

  the relative sizes respectively equal to 0.93 and 1.

  Preferably, the profiles constituting said blades are

those to be defined below.

  The figures of the annexed drawing will make clear how

the invention can be realized.

  FIG. 1 is a partial view of the rear portion of a helicopter having a shrouded rotor arrangement generating a transverse air flow to balance the driving torque of the main lift rotor.

(not shown)

  FIG. 2 is an enlarged section along line II-II of FIG.

Figure 1.

  Figure 3 shows in perspective a rotor blade

according to the present invention.

  FIGS. 4a, 4b and 4c are sections of the blade shown in FIG. 3, respectively according to the plans

  a-a, b-b and c-c of this last figure.

  FIGS. 5a, 5b, 5c and 5d schematically illustrate, along the span of the blade counted from the axis of rotation XX of the rotor, respectively the planar shape of an embodiment of said blade, the relative camber variation, twisting variation and variation

of relative thickness.

262,806?

  FIGS. 6a to 6e schematically represent five profiles referenced I to V, corresponding to five sections

  particular of the blade along its span.

  Figure 7 is a diagram showing the camber of profiles I to V of Figures 6a to 6e. FIG. 8 shows, as a function of the maximum lift coefficient, the variation of the merit figure of a rotor equipped with blades according to the invention, in comparison with a

known rotor ..

  The helicopter tail 1 shown in FIGS. 1 and 2 comprises a fuselage portion 2 and a vertical drift 3. At the base of the vertical drift 3 is arranged a tunnel 4 passing through the fuselage portion 2 from one end to the other. so that this tunnel has an air inlet 5 on one side of the fuselage and an air outlet 6 on the other side of said

fuselage (see Figure 2).

  The tunnel 4 has a form of revolution around a

  X-X axis, transverse to the L-L longitudinal axis of the helicopter

  tery. For example, the air inlet 5 has a rounded peripheral edge 7 which is extended, towards the air outlet 6, by a cylindrical portion 8 itself prolonged

  to said air outlet 6 by a diverging 9.

  In the tunnel 4 is mounted a rotary hub 10 provided with a plurality of blades 11. This rotary hub 10 is carried by a fixed hub 12 integral with the structure of the helicopter via three arms 13a, 13b and 13b. 13c. The rotary hub 10 and the fixed hub 12 are of cylindrical shape and are centered on the axis XX of the tunnel 4. The rotary hub 10 is disposed on the side of the air inlet 5, so that for example the ends of the 11 are located next to the cylindrical portion 8 of the tunnel 4, while

  the fixed hub 12 is on the side of the air outlet 6.

9 26? 806?

  1 In known manner, inside the fixed hub 12 is a mechanism 14 for rotating the rotating hub, itself driven by a shaft 15, driven by the main motor or motors (not shown) of the aircraft intended for training the lift rotary wing (also not shown). Thus, as explained above, the blades 11 of the rotary hub 10 create the air flow that generates the transverse thrust

  necessary to balance the yaw of the helicopter.

  Also known, for varying the intensity of this transverse thrust, is provided, within the fixed hub 12, and partially of the rotary hub 10, a system 16 for controlling the pitch angle of the blades 11,

  operated via a control rod 17.

  The feet 18 of the blades 11 are rotatably mounted on the hub

  10 and are connected to the pitch control system 16.

  Said blade roots 18 are connected to the retaining and driving mechanism 14 by torsion beams 19. As shown in FIG. 2, one of the support arms 13a of the fixed hub 12 serves as a fairing for the shaft 15 and to the

control rod 17.

  The arms 13a, 13b and 13c may be uniformly distributed at around 120. of the X-X axis and arranged with some

  relative offset behind the plane of the blades 11.

  In Figure 3, there is shown in perspective, a blade 11 of the rotary hub 10, with its blade root 18 and its torsion beam 19, apart from said hub. It also shows the axis of rotation X-X of the rotary hub 10, and a portion 27 of the fastening means of the connecting rod 19, and therefore of the blade 11, to the mechanism of

restraint and training 14.

26? 8062

  The blade 11 comprises, in plan view, a line of rectilinear leading edge 28. The trailing edge line 29 is also rectilinear. In addition, the straight lines of leading edge 28 and trailing edge 29 are parallel to each other.

  Thus, in plan, the blade 11 has a rectangular shape

  re, with a constant profile cord from the foot of

  blade 18 to its outer end section 30.

  The blade 11 has a span R, counted from the axis of rotation XX of the rotary hub 10. Hereinafter, the span position of a profile (or section) of the blade 11 will be designated by the distance r separating this profile (or this section) from the axis of rotation XX of said rotary hub 10 and more especially by the relative span r R

corresponding to this position.

  The pitch control axis 31 of the blade 11 is parallel to the

  lines 28 and 29 leading edge and trailing edge.

  The sections of the blade 11 shown in FIGS. 4a, 4b and 4c respectively correspond to the sectional planes aa, bb and cc of FIG. 3, that is to say to planes whose relative dimensions r to the axis XX are respectively

equal to 100%, 73% and 45%.

  The sections of FIGS. 4a, 4b and 4c show that the axis of the twist v of the blade in span is merged with the pitch control axis 31 and that this twist axis, which is distant from the edge line of FIG. attack 28 by a distance d close to 39% of the length of the rope 1, passes through the mid-thickness plane 32 of the corresponding profiles, this plane

  32 being parallel to the plane of the ropes 33.

  he 26? 806? Figures 4a, 4b and 4c further show that the thickness, twisting and camber of the blade 11 vary greatly

in scope.

  In the exemplary embodiment of a blade 11 according to the invention, illustrated by FIGS. 5a to 5d, it can be seen that the distance separating the axis XX from the fastening means 27 is equal to 0.095R, that the torsion beam 19 extends from 0.095 R to 0.38 R, that the blade root 18 extends from 0.38 R to 0.45 R and that the aerodynamically active portion of the blade 11 itself extends from 0, 45 R to R. The maximum relative camber K / 1 (that is to say reported to the rope 1) of the successive profiles constituting the aerodynamically active portion of said blade is negative and grows by a value equal to -0.013 for the section blade root 18 arranged at 0.40 R up to 0 for the blade root section 18 arranged at 0.25 R. Between 0.25 R and 0.845 R, the maximum relative camber of the profiles of the aerodynamically active portion of the blade 11 increases strongly and regularly (and preferably substantially linearly) from the value 0 to a value close to 0.036, in pa with a value close to 0.01 for the blade section at 0.53 R and a value close to 0.02 for the section at 0.66 R. Between 0.845 R and 0.93 R, the camber relative maximum increases slightly from 0.036 to 0.038 and then remains constant at

  value 0.038 between 0.93 R and R (see Figure 5b).

  As illustrated in FIG. 5c, the kinking v of the blade root 18 strongly increases from 0.038 R to 0.45 R from 8 to 11.9. From 0.45 R to 0.86 R, the twist of the blade 11 decreases from 11.90 to 3.7, passing through the values 6.99 to 0.61 R and 4.6 to 0.73 R. from 0.86 R to R, twisting increases again from 3.70 to 4.60. Preferably, between 0.45

  R and R, the twist variation v is at least sensitive-

parabolic.

12 to 8062

  1 The maximum relative thickness e of the blade root 18 and the blade 11 decreases linearly from the value 13.9% for the section arranged at 0.40 R to 9.5% for the section arranged at 0.93 R in passing through the values 12, 8%, 11.7% and 10.2% respectively for the sections arranged at 0.53 R, 0.66 R and 0.845 R. Between 0.93 R and R, this relative thickness is

  constant and equal to 9.5% (see Figure 5d).

  Thus, to generate the blade 11 and its blade root 18, it is possible to define a number of basic profiles intended to constitute specific sections thereof and to regularly evolve the intermediate profiles of a portion of blade between two basic profiles, to satisfy changes in thickness and relative camber. It then suffices to wedge each of said basic profiles and said intermediate profiles around

  the twist axis 31 to obtain said blade.

  For example, for this purpose, it is possible to define five basic profiles respectively bearing the following references I, II, III, IV and V and having respective relative maximum thicknesses equal to 9.5%, 10.2%, 11 , 7%, 12.8% and 13.9%. Thus, the base profile I will be used between R and 0.93 R, while the profiles II, III, IV and V will respectively be arranged at the sections located at 0.845 R, 0.66 R, 0.53 R and 0, A. The definitions are given below.

  such profiles, compared to a system of rectangular axes

  OX, OY, which for each of them originates from the leading edge 28, the abscissa axis OX coinciding with the rope and being oriented from the leading edge 28 to the trailing edge 29 (for profiles I, II, III and IV) or 34 (for profile V), as shown in FIGS. 6a to 6e. A - Example of profile I having a relative maximum thickness equal to 9.5% and usable between R and 0.93 R (see

Figure 6a).

26? 806_-

  1 Such a profile I can be such that: - the reduced ordinates of its extrados line 35 are given between X / l = O and X / l = 0.39433, by the formula (1) Y / 1 = fl ( X / 1) 1/2 + f2 (X / 1) + f3 (X / 1) 2 + f4 (X / 1) 3 + f5 (X / 1) 4 + f6 (X / 1) 5 + f7 (X / l) 6 with fl = + 0.16227 f2 = - 0.11104.10-1 f3 = + 0.13247 f4 = - 0.25016.10 f5 = + 0.10682.102 f6 = - 0.22210.102 f7 = + 0.17726. 102 between X / 1 = 0.39433 and X / 1 = 1, by the formula (2) Y / 1 = gO + gl (X / 1) + g2 (X / 1) 2 + g3 (X / 1) 3 + g4 (X / 1) 4 + gS (X / 1) 5+ g6 (X / 1) 6 with gO = + 0.22968 gl = - 0.17493.10 g2 = + 0.77952.10 g3 = - 0.17457.102 g4 = + 0.20845.102 g5 = - 0.13004.102 g6 = + 0.33371.10 - whereas the reduced ordinates of the intrados line 36 of said profile are given between X / l = O and X / l = 0.11862, by the formula (3) Y / 1 = hl (X / 1) V 2 + h 2 (X / 1) + h 3 (X / 1) 2 + h 4 (X / 1) 3 + h 5 (X / 1) 4 + h 6 ( X / 1) 5 + h7 (X / 1) 6 with hl = -0.13971 h2 = + 0.10480.10-3 h3 = + 0.51698.10 h4 = - 0.111297.103 h5 = +0.14695.104 h6 = - ' 0.96403. 104 hr = + 0.24769.105

26? 8062

  1. between X / l = 0.11662 and X / l = 1, by the formula (4) Y / 1 = iO + il (X / 1) + i2 (X / 1) 2 + i3 (X / 1) 3 + 14 (X / 1) 4 + 15 (X / 1) 5 + 16 (X / 1) 6 with 10 = 0.25915. 10-1 II = - 0.96597.10-1 i2 = + 0.49503 i3 = + 0.60418.10-1 i4 = - 0, 17206.10 i5 = + 0.20619.10 i6 = - 0.77922 B) Example of profile II having a maximum relative thickness equal to 10.2% and usable for a section of blade disoosed at 018L15 R (Figure 6b) For this profile II: - the reduced ordinates of the extrados line 35 are given between X / l = O and X / 1 = 0.39503, by the formula (5) Y / 1 = jl (X / 1) .V 2 + j 2 (X / 1) + j 3 (X / 1) 2 + j 4 (X / 1) 3 + j5 (X / 1) 4+ j6 (X / 1) 5 + j7 (X / 1) 6 with j1 = + 0.148683 j2 = -0.67115.10-2 j3 = + 0.44720 j4 = - 0.36828.10 ## EQU2 ## between X / 1 = 0.39503 and X / 1 = 1, by the formula (6) Y / 1 = kO + kl (X / l) ) + k2 (X / 1) 2 + k3 (X / 1) 3 + k4 (X / 1) 4 + k5 (X / 1) 5+ k6 (X / 1) 6 with kO = + 0.45955 kl = - 0.39834.10 k2 = + 0.16726.102 k3 = 0.35737 102 k4 = + 0.41088 102 k5 = - 0.24557.102 k6 = + 0.60088.10

2698062

  1 - whereas the reduced ordinates of the intrados line 36 of said profile are given between X / 1 = O and X / 1 = 0.14473, by the formula (7) Y / 1 = ml (X / 1) V 2 + m2 (X / l) + m3 (X / l) 2 + m4 (X / 1) 3 + m5 (X / l) + m6 (X / 1) 5 + m7 (X / l) 6 with ml = - 0,13297 m2 = + 0.36163.10-1 m3 = + 0.17284.10 m4 = 0.27664.102 m5 = + 0.30633.103 m6 = - 0.16978.104 m7 = + 0.36477.104 between X / l = 0.14473 and X / l = 1, by the formula (8) Y / 1 = n + n (X / 1) + n 2 (X / 1) 2 + n 3 (X / 1) 3 + n 4 (X / 1) 4 + n ( X / 1) 5 + n6 (X / 1) 6 with nO = - 0.30824. 10-1 n1 = - 0.20564.10-1 n2 = - 0.21738 n3 = + 0.24105.10 n4 = - 0.53752. N5 = + 0.48110.10 n6 = - 0,15826.10 C) Example of profile III before a relative maximum thickness equal to 11.7% and usable for a section of blade arranged at 0.66 R (FIG. 6C) For this profile III, - the reduced ordinates of the extrados line 35 are given between X / 1 = O and X / 1 = 0, 28515, by the formula (9) Y / 1 = tl (X / 1) 1v2 + t2 ( X / 1) + t3 (X / 1) 2 + t4 (X / 1) 3 + t5 (X / 1) 4 + t6 (X / 1) 5 + t7 (X / 1) 6 with tl = + 0, 21599 t2 = - 0.17294 t3 = + 0.22044.10 t4 = - 0.26595.102 t5 = + 0.144242.103

16 2628062

  1 t6 = - 0.39764.103 t7 = + 0.42259.103 between X / 1 = 0.28515 and X / 1 = 1, by the formula (10) Y / 1 = uO + u1 (X / 1) + u2 (X / 1) 2 + u3 (X / 1) 3 + u4 (X / 1) 4 + u5 (X / 1) 5 + u6 (X / 1) 6 with uO = + 0.39521.10-1 ul = +0, 26170 u2 = -0.47274 u3 = -0.40872 u4 = +0.15968.10 u5 = -0.15222.10 u6 = +0.51057 - while the reduced ordinates of the intrados line 36 of said profile are given between X / 1 = 0 and X / 1 = 0.17428, by the formula (11) Y / 1 = v1 (X / 1) 1/2 + v2 (X / 1) + v3 (X / 1) 2 + v4 ( X / 1) 3 + v5 (X / 1) 4 + v6 (X / 1) 5 + v7 (X / 1) 6 with v1 = -0.16526

v2 = -0.31162.10-

  v3 = +0.57567.10 v4 = -0.10148.103 v5 = +0.95843.103 v6 = -0.44161.104 v7 = +0.78519.104 25. between X / 1 = 0.17428 and X / 1 = 1, by the formula (12) Y / 1 = w0 + w1 (X / 1) + w2 (X / 1) 2 + w3 (X / 1) 3 + w4 (X / 1) 4 + w5 (X / 1) 5 + w6 ( X / 1) 6 with w0 = -0,25152.10-1 w1 = -0,22525 w2 = +0,89038 w3 = -0,10131.10 w4 = +0,16240 w5 = +0,46968 w6 =, - 0, 26400

17 2628062

  1 D) Example of profile IV having a relative maximum thickness equal to 12.8% and usable for a section of blade arranged at 0.53R (FIG. 6d) For this profile IV, the reduced ordinates of the extrados line 35 are given between X / l = 0 and X / l = 0.26861, by the formula (13) Y / 1 = al (X / 1) v 2 + a 2 (X / 1) + c 3 (X / 1) 2 + a4 (X / 1) 3 + c5 (X / 1) 4+ a6 (X / 1) 5 + m7 (X / 1) 6 with al = +0.19762 m2 = +0.17213 a3 = -0.53137.10 a4 = +0.56025.102 a5 = -0.32319.103 a6 = +0.92088.103 c7 = -0.10229.104 between X / l = 0.26861 and X / l = 1, by the formula (14) Y / l = B + B1 (X / 1) + t2 (X / 1) 2 + 53 (X / 1) 3 + B4 (X / 1) 4

+ B5 (X / 1) 5 + 56 (X / 1) 6

with B0 = + 0.28999.10-1

B1 = +0.38869

32 = -0.10798.10

B3 = +0.80848

54 = +0.45025

35 = -0.10636.10

36 = + 0.47182

  while the reduced ordinates of the intrados line 36 of said profile are given between X / 1 = 0 and X / 1 = 0.20934, by the formula (15) Y / 1 = yl (X / 1) V 2 + Y 2 (X / 1) + Y 3 (X / 1) 2 + Y 4 (X / 1) 3 + Y 5 (X / 1) 4 + y 6 (X / 1) 5 + y 7 (X / 1) 6 with yl = -0.25376

Y2 = +0.61860

Y3 = -0.96212.10

Y4 = +0.12843.103

18 262806?

1 5 = -0.90701.103

y6 = +0.32291.10

Y7: -0.45418. 104

  between X / 1 = 0.20934 and X / 1 = 1, by the formula (16) Y / 1 = 60 + 161 (X / 1) + 62 (X / 1) 2 + 63 (X / 1) 3 + 64 (X / 1) + 65 (X / 1) 5 + 66 (X / 1) 6 with 60 = -0.25234.101 1l = -0.32995

62 = +0.10890.10

63 = -0.10066.1064 = -0.32520

= +0,11326.10

66 = -0.64043

  E) Example of profile V having a relative maximum thickness equal to 13.9% and usable for a foot section of Dale arranged at 0.40 R (FIG. 6R) For this profile V, the reduced ordinates of the line of FIG. extrados 35 are given 20. between X / l = 0 and X / l = 0.19606, by the formula V2 (17) Y / l = el (X / 1) + c2 (X / 1) + E3 (X / l) 2 + E4 (X / 1) 3 + c5 (X / 1) 4 + E6 (X / 1) 5 + ú7 (X / 1) 6 with el = +0,22917 e2 = -0,22972

C3 = +0.21262.10

E4 = -0.39557.102

= +0.32628.103

  c6 = -0.13077.104 c7 = +0.20370.104 30. between X / I = 0.19606 and X / I = 1, by the formula (18) Y / 1 = OXO + X1 (X / 1) +% 2 (X / 1) 2 + X 3 (X / 1) 3 + 4 (X / 1) 4

+ X5 (X / 1) 5 + 6 (X /) 6

  with 0XO = + 0.32500.10-1 xl = +0.29684

X2 = -0.99723

2628062.

3 = + 0.82973

) 4 = +0.40616

) 5: -0.10053.10

) = + 0.44222

  - whereas the reduced ordinates of the intrados line 36 of said profile are given between X / l = 0 and X / l = 0.26478, by the formula (19) Y / l = il (X / 1) 2 + p2 (X / 1) + P3 (X / 1) 2 + -4 (X / 1) 3 + 05 (X / 1) 4 + p6 (X / 1) 5 + P7 (X / 1) 6 with P = -0.19314

P2 = -0.22031

P3 = +0.44399.10

U4 = -0.41389.102

P5 = +0.23230.103

u6 = -0.66179.103

U7 = +0.74216.103

  between X / 1 = 0.26478 and X / 1 = 1, by the formula (20) Y / 1 = v 0 + v 1 (X / i) + v 2 (X / 1) 2 + v 3 (X / 1) 3 + v4 (X / 1) 4 + v5 (X / 1) 5 + v6 (X / 1) 6 with VO = -0.42417. 10-1 vl = -0.29191

V2 = +0.57883

V3 = +0.41309

  v4 = -0.19045.10 v5 = +0.18776.10 v6 = -0.63583 In FIG. 7, the evolution of the relative maximum camber K / l of each of said profiles I to V in FIG.

  function of the reduced abscissa X / l.

  These different profiles I to V, defined above using specific equations, are actually part of a family of profiles, each of which can be determined

2628062

  by a law of variation of thickness and a law of arching along the chord of the profile, according to the technique, which is defined on page 112 of the report "Theory of wing sections" of H. ABOTT and E. VON DOENHOFF published in 1949 by Mc GRAW HILL BOOK Company, Inc. and according to which the coordinates of a profile are obtained by postponing

  and other of the middle line, or skeleton, and perpendicular

  Cultively to it, the half thickness at this point.

  To define the profiles of the family to which

  hold the profiles I to V, the following analytical formulas are advantageously used for the mean line and the thickness law: - for the average line or skeleton: (21) Y / l = cl (X / 1) + c2 (X / l) 2 + c3 (X / 1) 3 + c4 (X / 1) 4 + c5 (X / 1) 5 + c6 (X / 1) 6 + c7 (X / 1) 7 - for the law of thickness: (22) ye / l = b1 (X / 1) + b2- (X / 1) 2 + b3 (X / 1) 3 + b4 (X / 1) 4 + b5 (X / i) 5 ± b6 (X / 1) 6 + b7 (X / 1) 7+ b8 (X / 1) 8 + b9 (X / 1) 9 + blO (X / 1) For the blade profiles according to the invention, of which relative thickness is between 9% and 15%, each coefficient b1 to b10 of the formula (22) can be advantageously defined by the corresponding formula (23.1) to (23.10), given below: (23.1) b1 = b11 (e / 1) + b12 (e / 1) 2 + b13 (e / 1) 3 + b14 (e / 1) 4 + b15 (e / 1) 5+ b16 (e / 1) 6 (23.2) b2 = b21 (e / w) + b22 (e / w) 2+ b23 (e / 1) 3+ b24 (e / 1) 4 + b25 (e / 1) 5+ b26 (e / w) 6

  .......... DTD: 30 ..................................... ..............

  (23.10) b10 = b101 (e / l) + b102 (e / l) 2 + b103 (e / 1) 3 + b104 (e / 1) 4 + b105 (e / 1) 5 + b106 (e / l) 6

21 2628062

  The different coefficients b1 to b106 then have the following values: b1 = +0.98542.105 b61 = -0.18709.1010 b12 = -0.43028.10 7 b62 = +0.82093. 1011 b13 = +0.74825.108 b63 = -0.14340.1013 b14 = -0.64769.109 b64 = +0, 12464.1014 b15 = +0.27908.1010 b65 = -0.53912.1014 b16 = -0.47889.10 10 b66 = +0.92831.1014 b21 = -0.33352.107 b71 = +0.25348.1010 b22 = +0.14610. 109 b72 = -0.111123.1012 b23 = -0.25480.1010 b73 = +0.194411.1013 b24 = +0, 22115.1011 b74 = -0.168810.1014 b25 = -0.95525.1011 b75 = +0.73066.1014 b26 = +0.16428.1012 b76 = -0.12582.1015 b31 = +0.39832.108 b81 = -0.20869. 1010 b32 = -0.17465.1010 b82 = +0.91583.1011 b33 = +0.30488.1011 b83 = -0, 16000.1013 b34 = -0.26484.10 22 b84 = +0.13909.1014 b35 = +0.11444.1010 b85 = -0.60166.1014 b36 = -0.19704.1013 b86 = +0.10361.1015 b41 = -0, 24305.109 b91 = +0.95554.109 b42 = +0.10661.1011 b92 = -0.41936.10lo b43 = -0.18618.1012 b93 = +0.73266.1012 b44 = +0.16178.1013 b94 = -0.63693. 1013 b45 = -0.69957.1013 b95 = +0.27553.1014 b46 = +0.12043.1014 b96 = -0.47450.1014 b51 = +0.86049. 109 b101 = -0.18663.10 b52 = -0.37753.10 11 b102 = +0.81909.1010 b53 = +0.65939.1012 b103 = -0.13411.10 12 b54 = -0, 57309.10 13 b104 = +0.12281.1012 b55 = +0 , 24785.1014 b105 = -0.58321.1013 b56 = -0.42674.10 14 b106 = +0.92688.1013

22 2628062

  1 Similarly, for relative maximum backbones of between -2% and + 5% of the chord, each coefficient c1 to c7 of the formula (21) giving the shape of the skeleton may advantageously be defined by the formula (24.1 ) to (24.7), given below: (24.1) cl = c11 (e / l) + c12 (e / 1) 2 + c13 (e / 1) 3 + c14 (e / 1) 4 + c15 ( e / 1) 5 + c16 (e / w) 6 (24.2) c2 = c21 (e / w) + c22 (e / w) 2 + c23 (e / 1) 3 + c24 (e / 1) 4 + c25 (e / 1) 5+ c26 (e / l) 6

  ................................................. 10 ........

  (24.7) c7 = c71 (e / 1) + c72 (e / 1) 2 + c73 (e / 1) 3 + c74 (e / 1) 4 + c75 (e / 1) 5 + c76 (e / 1) 6

  The various coefficients c1 to c76 advantageously have

  the following values: cl = -0.29874.101 c51 = -0.18750.104 c12 = 0.61332.102. c52 = +0.72410.105 c13 = +0.60890.105 c53: +0.90745.107 c14 = -0.43208.106 c54: -0.54687.109 c15 = -0.12037.109. c55 = +0.58423.1010 c16 = +0.24680.1010 c56 = +0.50242.1011 c21 +0,17666.102 c61 = +0.12366. C22 = +0.70530.104 c62 = -0.43178.105 c23 = -0.40637.106 c63 = -0.61307.107 25. c24 = -0.28310.108 c64 = +0.33946.109 c25 = +0.20813.1010 c65 = -0, 26651.1010 c26 = -0.31463.1011 c66 = -0.49209.1011 c31 = -0.38189. 103 c71 = -0.31247.103 c32 = +0.31787.102 c72 = -0.83939.104 c33 = +0, 23684.104 c73 = +0.16280.107 c34 = -0.47636.108 c74 = -0.74431.108

23 2628062

  1c35 = -0.26705.1010 c75 = +0.30520.108 c36 = +0.65378.1011 c76 = +0, 21265.1011 c41 = +0.13180.104 c42 = -0.44650.105 c43 = -0.65945.107 c44 = +0.35822.109 c45 = -0.24986.1010 c46 = -0.58675.10î The analytical formulas above allow, once chosen, the evolution of the thickness law according to the span of the blade (see figure 5d) and the evolution maximum camber with wingspan (see Figure 5b)

  to define the geometry of the complete blade.

  In order to verify the effectiveness of the present invention, a tail rotor arrangement of the type described with reference to FIGS. 1 and 2 was constructed and the following experiments were carried out: a) firstly, the rotary hub 10 was equipped with of thirteen blades 11, each consisting of the constant profile NACA 63A312, with a constant twist, and the curve giving the merit figure FM of said arrangement is plotted as a function of the average lift coefficient per blade Cz, which is defined by the formula Cz = 3T opbl R 2 in which T, a, p, 1 and R are respectively the thrust or the total traction of the rotor, the diffusion coefficient of the aerodynamic flow, the density of the air, the rope of the blade and the radius of the propeller, as defined above, and b the number of blades and U la

  peripheral speed of the propeller.

24 2628062

  Curve A of FIG. 8 was obtained.

  b) then, the thirteen preceding blades were replaced by thirteen blades according to the present invention and

restarted the measurements.

  Curve B of FIG. 8 has been obtained. These curves show that the maximum merit figure FM and the maximum coefficient of lift per maximum blade of the rotor arrangement tested under b) are respectively 2.8% higher and 8% .with respect to the sizes

  of the rotor arrangement tested under (a).

  We also see on these curves that the improvement of the figure of merit is obtained whatever the level of

average load per blade.

* 2,628,062.

Claims (25)

  1 1 - Blade for keeled propeller comprising a tunnel (4) and a rotor with multiple blades (11) coaxial with said tunnel (4), said rotor comprising a rotary hub (10) whose radius is of the order of 40% of that of said tunnel (4) and on which said blades (11) are mounted via blade roots (18), characterized in that, in plan, the aerodynamically active portion of said blade has, beyond the blade root (18), a rectangular shape so that the successive profiles constituting said aerodynamically active portion all have the same rope 1 and that the end section (30) of said aerodynamically active portion is straight; and in that, along the span of the blade counted from the axis of the tunnel, between a first section whose relative span is close to 45% and the end section (30) of said blade: the maximum relative camber of the successive profiles constituting said aerodynamically active portion of the blade is positive and increases from a value close to 0 to a value close to 0.04; the twisting (v) of said aerodynamically active portion of the blade decreases from a first value close to 12 to said first section to a second value close to 40 to a second section whose relative span is close to 0.86 and then increases from this second section to a third value close to 4.50 at said blade end section; and the relative maximum thickness of said successive profiles decreases from a value close to 13.5% to a value close to 9.5%. 262,28062   1 2 - Blade for keeled propeller according to claim 1, characterized in that said relative maximum camber increases almost linearly from this value close to 0 to a value equal to 0.036 for a relative span equal to 0.845, passing through the values 0.01 and 0.02 respectively for the relative sizes 0.53 and 0.66, then increases from this value equal to 0.036 for the relative span equal to 0.845 to a value equal to 0.038 for the relative span equal to 0.93 and finally is constant and   equal to 0.038 between the relative sizes 0.93 and 1.   3 - blade-for faired propeller according to one of the claims   i or 2, characterized in that the foot (18) of said blade (11) has evolutive profiles whose relative maximum camber is negative and increases by a value substantially equal to -0.013 for a relative span equal to 0.40 at said value close to 0 for a span relative equals 0.45.   4 - Blade for keel propeller according to claim 1, -   characterized in that, between the relative sizes 0.45 and 1, the twisting evolution is at least substantially   parabolic, with minimum at the relative span of 0.86.   - Keel for faired propeller according to claim 4, characterized in that the axis (31) of twisting said aerodynamically active portion is parallel to the line (28) leading edge and the line (29) edge of leakage thereof and is remote from said leading edge line (28) by a distance d approximately equal to 39% of   the length of the chord of the profiles. 27 262806?   1 6 - blade for keeled propeller according to claim 5, characterized in that the rotation of the foot (18) of said blade (11) increases from said value close to 8 to a relative size close to 0.38 to said neighboring value from 120 for the relative span to 0.45. 7 - Blade for keel propeller according to claim 1, characterized in that the maximum relative thickness of the decolt profiles. linearly with a value close to 13.9% for a relative span equal to 0.40 to a value close to 9.5% for a relative span equal to 0.93, and is constant and equal to said value close to 9 , 5% between the relative widths respectively equal to 0.93 and 1. 8 - blade for faired propeller according to claim 7,   characterized in that the portion of the aerodynamic portion   the effective range between relative spans 0.93 and 1 is constituted by a profile (I) having a relative maximum thickness equal to 9.5% and such that, depending on the reduced abscissa X / l along the rope , counted from the leading edge, - the reduced coordinates of its extrades line (35) are given between X / l = 0 and X / 1 = 0.39433, by the formula (1) Y / l = fl (X / 1) 1V2 ± f2 (X / 1) + f3 (X / 1) 2 + f4 (X / 1) 3 + f5 (X / 1) 4 + f6 (X / 1) 5 + f7 (X / l) 6 with fl = + 0.16227 f2 = -0.111704.10-1 f3 = + 0.13247 f4 = -0.25016.10 28 262806?   Δ = +0.10682.102 f6 = -0.22210.102 f7 = +0.17726.102 between X / l = 0, 39433 and X / 1 = 1, by the formula (2) Y / l = gO + gl (X / l) + g2 (X / 1) 2 + g3 (X / 1) 3 + g4 (X / 1) 4 + g5 (X / 1) 5+ g6 (X / 1) 6 with gO = + 0.22968 g = -0,17493.10 g2 = + 0.77952.10 g3 = -0,17457.102 g4 = +0,20845.102 g5 = -0,13004.102 g6 = +0, 33371.10 - while the reduced ordinates of the intrados line (36) of said profile are given between X / 1 = O and X / 1 = 0.11662, by the formula (3) Y / 1 = hl (X / 1) V 2 + h 2 (X / 1) + h 3 (X / 1) 2 + h 4 (X / 1) 3 + h 5 (X / 1) 4 + h 6 (X / 1) 5 + h 7 (X / 1) 6 with h 1 = -0.13.91 h 2 = + 0.10480 × 3 - h 3 = +0.51698.10 h4 = -0, 11297.103 h5 = +0.14695.104 h6 = -0.96403.104 h7 = +0.24769.105 between X / l = 0.11862 and X / 1 = 1, by the formula (13) Y / l = iO + il (X / 1) + i2 (X / 1) 2 + i3 (X / 1) 3 + i4 (X / 1) 4 + i5 (X / 1) 5 + 16 (X / 1) 6 with iO = -0.25915.10-1 il = -0, 96597.10-1 i2 = +0.49503 i3 = + 0.60418.10-1 i4 = -0.117206.10 i5 = +0, 20619.10 i6 = -0.77922 29 2628062   1 9 - Blade for faired propeller according to any one of claims 7 or 8,   characterized in that the profile of the blade section disposed at the relative span of 0.845 has a relative maximum thickness of 10.2% and is such that, depending on the reduced abscissa X / 1 along the rope , counted from the leading edge, - the reduced ordinates of the extrados line (35) are given as 10. between X / 1 = 0 and X / 1 = 0.39503, by the formula (5) Y / l = jl (X / l)% 2 + j2 (X / l) + j3 (X / 1) 2 + j4 (X / 1) 3 + j5 (X / 1) 4+ j6 (X / 1) 5 + j7 (X / 1) 6 with j1 = +0.14683 j2 = -0.67115.1032 j3 = +0.474720 j4 = -0.36828.10 j5 = +0.112651.102 j6 = -0.23835.102 j7 = +0.118155 . 20. between X / 1 = 0.39503 and X / 1 = 1, by the formula (6) Y / 1 = kO + k1 (X / 1) + k2 (X / 1) 2 + k3 (X / 1) ) 3 + k4 (X / 1) 4 + k5 (X / 1) 5 + k6 (X / 1) 6 with kO = +0.45955 k1 = -0.39834.10 k2 = +0.16726.102 k3 = -0, 35737.102 k4 = +0.41088.102 k5 = -0.24557.102 k6 +0.60088.10 - whereas the reduced ordinates of the intrados line (36) of said profile are given between X / 1 = O and X / 1 = 0, 14473, by the formula (7) Y / l = ml (X / 1) / 2 + m2 (X / 1) + m3 (X / 1) 2 + m4 (X / 1) 3 + m5 (X / l) 4 + m6 (X / 1) 5 + m7 (X / 1) 6 2628062   1 with ml = -0.13297 m2 = + 0.36163.10-1 m3 = '+ 0.17284.10 m4 = -0.27664.10 m5 = +0.30633.103 m6 = -0.16978.104 m7 = +0.36477.104 between X / 1 = 0.14473 and X / 1 = 1, by the formula (8) Y / 1 = n 0 + n 1 (X / 1) + n 2 (X / 1) 2 + n 3 (X / 1) 3 + n 4 (X / 1) 4 + n5 (X / 1) 5 + n6 (X / 1) 6 with n0 = -0.30824.10-1 ni = -0.20564.10-1 n2 = -0.21738 n3 = +0.24105.10 n4 = -0.53752.10 n5 = +0.48110.10 n6 = -0, 15826.10 - Blade for keeled propeller according to any one of Claims 7 to 9,   characterized in that the profile of the blade section disposed at the relative span of 0.66 has a relative maximum thickness of 11.7% and is such that, depending on the reduced abscissa X / 1 along the rope, counted from the leading edge, - the reduced ordinates of the extrados line are given between X / 1 = O and X / 1 = 0.28515, by the formula (9) Y / l = tl (X / 1) 12 + t2 (X / 1) + t3 (X / 1) 2 + t4 (X / 1) 3 + t5 (X / 1) 4 + t6 (X / 1) 5 + t7 (X / 1) 1) 6 with tl = +0.21599 t2 = -0.17294 t3 = +0.22044.10 t4 = -0.26595.102 t5 = +0.144642.103 * t6 = -0.39764.103 t7 = +0.42259.103 2628062.   1. between X / 1 = 0.28515 and X / 1 = 1, by the formula (10) Y / 1 = uO + u1 (X / 1) + u2 (X / 1) 2 + u3 (X / 1) 3 + u4 (X / 1) 4 + u5 (X / 1) + u6 (X / 1) 6 with uO = +0.39521. 10 μl = +0.26170 u2 = -0.47274 u3 = -0.40872 u4 = +0.15968.10 u5 = -0.15222.10 u6 = +0.51057 - while the ordinates reduced of the intrados line of said profile are given between X / l = 0 and X / l = 0,17428, by the formula (11) Y / l = v1 (X / 1) / 2 + v2 (X / 1) + v3 (X / 1) 2 + v4 (X / 1) 3 + v5 (X / 1) 4 + v6 (X / 1) 5 + v7 (X / 1) 6 with v1 = -0.16526 v2 = -0.31162.10-   v3 = +0.57567.10 v4 = -0.10148.103 v5 = +0.95843.103 v6 = -0.44161.1C4 v7 = +0.78519.104 between X / 1 = 0.17428 and X / l = 1, by the formula ( 12) Y / l = w0 + wl (X / 1) + w2 (X / l) 2 + w3 (X / l) 3 + w4 (X / l) 4 + w5 (X / 1) 5 + w6 (X / l) 6 with w0 = -0.25152.10-1 w1 = -0.22525 w2 = +0.89038 w3 = -0.10131.10 w4 = +0, 16240 w5 = +0.46968 w6 = -0.26400 11 - Blade for faired propeller according to any one of Claims 7 to 10,   characterized in that the profile of the blade section disposed at the relative span of 0.53 R has a thickness 32 2628062   1 relative maximum equal to 13.8% and is such that depending on the reduced abscissa X / l along the chord, counted from the leading edge, - the reduced ordinates of the extrados line are given between X / 1 = 0 and X / 1 = 0.26861, by the formula (13) Y / 1 = al (X / 1) V 2 + a 2 (X / 1) + a 3 (X / 1) 2 + a 4 ( X / 1) 3 + a5 (X / 1) 4 + a6 (X / 1) 5 + a7 (X / 1) 6 with al = + 0.19762 a2 = +0.17213 a3 = -0.53137.10 a4 = +0.56025.102 a5 = -0.32319. 103 a6 = +0.92088.103 a7 = -0.10229.104 between X / 1 = 0.26861 and X / 1 = 1, by the formula (14) Y / 1 = B0 + 51 (X / 1) 62 (X / 1) 1) 2 + 3 (X / 1) 3 + 64 (X / 1) 4 + 65 (X / 1) 5+ B6 (X / 1) 6 with OO = + 0.28999.10'1 e1 = +0.38869 B2 = -0.10798.10 63 = +0.80848 B4 = +0.45025 = -0,10636.10 K6 = +0.47182   while the reduced ordinates of the intrados line of said profile are given between X / 1 = 0 and X / 1 = 0.20934, by the formula (15) Y / 1 = Y1 (X / 1) V2 + Y2 (X / 1) + y 3 (X / 1) 2 + Y 4 (X / 1) 3 + Y 5 (X / 1) 4 + y 6 (X / 1) 5 + y 7 (X / 1) 6 with Y 1 = -0 , 25376 y2 = +0.61860 y3 = -0.96212.10 y4 =. + 0.12843.103 33 2628062 Y5 = -0.90701.103   y6 = +0.32291.104 y7 = -0.45418.104 between X / l = 0.20934 and X / l = 1, by the formula (16) Y / l = 60 + 61 (X / 1) + 62 (X / l) 2 + 63 (X / 1) 3 + 64 (X / 1) 4 + 65 (X / 1) 5 + 66 (X / 1) 6 with 60 = -0,25234.10-1 61 = -0.32995 62 = + 0.10890.10 63 = -0.10066.10 64 = -0.32520 = +0,11326.10 66 = -0.64043   12 - Blade for faired propeller according to any one of claims 7 to 11,   characterized in that the profile of the blade root section disposed at the relative span 0.40 has a relative maximum thickness of 13.9% and is such that. as a function of the reduced abscissa X / l along the chord, counted from the leading edge, the reduced ordinates of the extrados line are given between X / 1 = 0 and X / 1 = 0, 19606, by the formula (17) Y / 1 = c 1 (X / 1) / 2 + c 2 (X / 1) + E 3 (X / 1) 2 + c 4 (X / 1) 3 + E 5 (X / 1) ) 4 + 6 (X / 1) 5 + c7 (X / 1) 6 with cl = +0.22917 c2 = -0.22972 c3 = +0.21262.10 c4 = -0, 39557.102 c5 = +0.32628.103 e6 = -0,13077.104 E7 = +0.20370.104 34 2628062   1. Between X / 1 = 0.19606 and X / 1 = 1, by the formula (18) Y / 1 = XO 0 + X 1 (X / 1) + X 2 (X / 1) 2 + X 3 (X / 1) 3 + 14 (X / 1) 4 + X5 (X / 1) 5 + X6 (X / 1) 6   with X0 = + 0.32500.10-1 X1 = +0.29684 12 = -0.99723 13 = + 0.82973 X4 = +0.40616 X5 = -0.10053.10 X6 = +0.44222   - while the reduced ordinates of the intrados line of said profile are given between X / 1 = 0 and X / 1 = 0.26478, by the formula (19) Y / 1 = pl (X / 1) V2 + P2 (X / 1) + p3 (X / 1) 2 + p4 (X / 1) 3 + p5 (X / 1) 4 + p6 (X / 1) 5 + P7 (X / 1) 6 with U1 = -0 , 19314 P2 = -0.22031 P3 = +0.44399.10 m4 = -0.41389.102 i5 = +0.23230.103 P6 = -0.66179.103 P7 = +0.74216.103   between X / 1 = 0.26478 and X / 1 = 1, by the formula (20) Y / 1 = v0 + v1 (X / 1) + v2 (X / 1) 2 + v3 (X / 1) 3 + v4 (X / 1) 4 + v5 (X / 1) 5 + v6 (X / 1) 6 with v0 = -0.42417. V1 = -0.29161 v2 = +0.57883 v3 = +0.41309 v4 = -0.19045.10 v5 = +0, 18776.10 v6 = -0.63583 2628062   1 13 - Propeller, characterized in that it comprises a plurality of blades   as specified under any one of the claims 1 to 12.   14 - Tail rotor arrangement for a rotary wing aircraft, characterized in that it comprises a plurality of blades   as specified under any one of the claims 1 to 12. 3, 13a3 2 X-X -1 1316   -. . - - -__. __ - -! _------- -, _ - -8ma   I 1 5 18 19 10 27 X 27 19 g 11 7_ T a j h- bed ["il'.16 7o 7 18 19 B02 7. \ 1 4 the. 27 I A l '1O-4o o' 0.2 0.4 0.6 0.8 1 1.2Cu He 6Z? CR I Z908z9z t '; 6 / 4_ -98'0 9'90 ú -_- --J__ 1 i1 i, i g I! i I I ! '-m ..- J-- -> - -.... - ': -' -ff ..... T-] T j I J 1 ____----, -.---- - ## EQU1 ## ** 0 ' _ ú I I XI I I   I _t ----- _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ssosI I9 '/' I   i I \ the bone I ,,, | K 'd I, /, f I i! -ElQo I '1 9 / tI 'g90O399 / 6 Z 36 A '' o o - o